Manufacture of leather.



OTTO ROHM, OF DAIRMSTAJJT, GERMANY.

MANUFACTURE OF LEATHER.

No Drawing.

To all whom it may concern:

Be it known that I, O'r'ro Ronni, subject of the German Emperor, residing at Darmstadt, Germany, have invented certain new and useful Improvements in the Manufacture or Treatment of Leather, of which the following is a specification.

Many attempts have been made to provide a substitute for the expensive yolks of eggs, which material is frequently adulterated and hitherto has been considered indispensable in the manufacture of laceleather or kid-leather. For instance itner has proposed the use of emulsions from albumins, fats and oils and Armand Muller- Jacobs the use of sulfurized oils instead of yolks of eggs, but neither of these processes has satisfied the requirements of a substitute for yolks of eggs. The leather becomes hard, thin and did not possess the feel which distinguishes the leather produced by means of yolks of eggs. 7 The effect of the sulfonated oils recommended by Armand Muller-Jacobs has been enhanced by adding to the same a volatile substance soluble in oil, for instance a liquid hydro carbon or ester, but the results obtained by these means were inferior to those produced with yolks of eggs.

I have discovered, that the insuflicient action of the sulfonated oils is due to the fact, that in the sulfonating and the subsequent neutralizing-process soaps are always produced, which during the tawing process form a compound of fatty acid with aluminium, a reaction which does not take place with yolks of eggs. If these soaps are removed from the oil solution, for instance by dialysis, there remains a perfect solution, whose effect not only equals that of the yolks of eggs, but surpasses the same. The leather becomes completely white,while the yolk-leather always has a yellowish tint, due to the coloring matter of the yolk; moreover, it becomes substantially fuller and softer than yolk-leather.

A further advantage is the possibility of working with an always uniform product, while the yolks of eggs, being a natural product, vary intheir composition and therefore act unequally, apart from frequent adulteratio'ns. According to the present invention the skins are therefore prepared in a manner similar to that required for the ordinary tawing (also'called alum-tanning) and yolk-process and are then subjected to Specmcation of Letters Patent.

Patented Nov. 1'7, 1914..

Application filed May 7, 1914. Serial No. 837,051.

a tawing and a softening process, in which instead of yolks of eggs a sulfonated oil or fat free from soap is used. All kinds of sulfonated oils and fats or mixtures of the same with unaltered oils or fats are suitable for the present purpose, provided that they yield with water an oil solution. The only essential condition is, that the soaps are removed by any convenient method, for instance by dialysis or by chemical means. A sulfonated oil, which contains no soap from the beginning, would, of course, be eminently suitable, but hitherto no means are known for preventing saponificationin the manufacture of sulfonated oils. A difficulty in using these fats and oils as a substitute for yolks of eggs consists in the fact, that they yield insoluble residues with the alum, which is indispensable in the manufacture of this kind of leather. Consequently, if in the manufacture of glac or kid-leather, all materials for the tawingand softening treatment are mixed together, as usual, the mass is liable to coagulate, so as to form lumps and become unsuitable. This defect may be avoided if the said process is divided into two stages, by causing the solution of sulfo-esters to act on the depilated hides independently of the alumsolution, the two being thus not added simultaneously, but the tawing solution being applied first and then the softening material or vice versa.

That the addition of volatile substances, such as toluene, acetic ester, etc., produces a favorable effect, has already been stated above in mentioning the work of Armand Muller-Jacobs. The reason for this phenomenon is obviously the finer distribution of the fat, produced by the said addition. This intensification of the effect renders it possible in some cases to work with less oil or fat.

Sulfurized oils or fats free from soap are suitable not only for the manufacture of glac or kid-leather, but generally for increasing the softness and fullness of other kinds of leather, especially leather tanned with vegetable tanning agents. The treatment with the said oil or fat may take place either during or after the tanning or tawing.

What I claim is 1. The process for softening leather, which cons sts in treating it with a sulfonated oil or fat free from soap, substantially asdescribed.

2. The process for preparing glac-leather, which consists in treating the depilated skin, first with a taWing liquld and then with a sulfonated oil or fat free from soap, substantially as described.

3. The process for preparing glac-leather, which consists in treating the depilated skins With a tawing liquid and then with a sulfionated oil free from soap and containing a volatile substance soluble in oil, substantially as described.

4:. The process for softening leather,

which consists in impregnating it with a mixture of a sulfonated oil or fat free from soap and unaltered oil or fat, substantially 15 as described.

In testimony whereof I have hereunto set my hand in presence of two subscribing Witnesses;

\ DR. OTTO ROI-1M.

Witnesses:

RICHARD KNUTTER, HUGO TRAV. 

